A Minnesota groom and 10 friends driving their RV to a bachelor party at Saturday's Kentucky Derby ended their trip abruptly after they stopped to pick up some friends, opened the storage bay, and found a corpse, authorities and the men said.

The men found the body late Thursday night in Winona, 118 miles (190 km) southeast of Minneapolis, when they opened a compartment that was accessible only from the outside of the RV, the Anoka County Sheriff Department said in a statement.

Officials said investigators have not identified the deceased or determined the cause of death.

"We will not speculate on any factors at this time," the sheriff's department said in its statement.

One of the men told a CBS television affiliate in Minneapolis that the group began its trip in Anoka, north of the Twin Cities, then stopped to pick up some friends at a Shopko store in Winona. They found the body when they were looking for more storage.

"At first some of us thought maybe it was a joke ... someone playing a prank on the groom," Jake Wanek told the television station. "We quickly realized that was not the case."

The group called authorities, who confiscated their luggage and the RV after interviewing the men, Wanek said.

Wanek told the TV station the bachelor party will not make it to Churchill Downs for the 140th running of the famed horse race on Saturday.

Later, Wanek tweeted: "The last 24 hours takes the cake but this has been the most eventful, exciting, depressing, unbelievable, epic, terrible weeks of my life."